Relative bioavailability and bioequivalence of entecavir dispersible tablets in healthy Chinese male volunteers

Abstract：Objective: To study the relative bioavailability and bioequivalence of entecavir dispersible tablets (Jiangsu Chia-Tai Tianqing Pharmacy Co. Ltd.) with reference to the entecavir tablets (Baraclude, Sino-A-merican Shanghai Squibb Pharmaceuticals Ltd.). Methods: In a randomized crossover study, 20 healthy Chinese male subjects received a single oral dose (0.5 mg) of either test or reference entecavir tablets after an overnight fast. The plasma concentrations of entecavir were determined by a validated LC-MS/MS method. The pharmacoki-netic parameters, the relative bioavailability and bioequivalence of two formulations were evaluated by DAS soft-ware. Results: After a single oral dose of 0.5 mg test or reference entecavir tablets, the pharmacokinetic parame-ters of entecavir were as follows : C_(max) (5.15±1.35) and (4.55±2.46) ng. ML~(-1); T_(max) (0.44±0.20) and (0.75± 0.31) h; t_(1/2) (147±127) and (127±48) h; AUC_(0-96) (13.7±2.6) and (13.0±1.9) ng·h·mL~(-1); AUC_(0-∞) (27.2±13.8) and (23.3±4.5) ng·h·mL~(-1); respectively. The relative bioavailability was (107.5±24.7)%. There were significant differences in T_(max) and C_(max) between two tablets, but no significant difference in AUC_(0-96) Conclusion: The test and reference entecavir tablets are bioequivalent in absorption. The slightly increased C_(max)and reduced T_(max)of the test formulation are obvious exhibition of its dispersible tablet characteristics.